1. Field of the Invention
The present invention relates to a method and apparatus for automatically scanning for defects in the density of a carpet during the manufacture of the carpet. More specifically, the invention relates to a method and apparatus for scanning a carpet for defects in the density of the tufts along the width of a carpet as it is being conveyed during its manufacture.
2. Related Art
In the manufacture of carpets, machines such as the Cobble Model Pantera are used to mass produce them. Such machines are designed to produce carpets with tufts that vary in density, pattern and color. In the course of producing the carpets, the machines may malfunction resulting in defects such as too much yarn being woven into the carpet, too little yarn being woven in, no yarn being woven into the carpet, holes, missed stitches, or low tuft lines. If the occurrence of defects are not carefully monitored, such defects may cause large amounts of material and machine hours to be wasted.
Consequently, quality control measures have been instituted by the manufacturers of carpets and other similar materials. However, such quality control measures are typically limited to the use of human operators observing the operation and output of the machines. When the operator sees a defect occurring, he/she stops the machine. The use of human operators has its limitations. Observing the output of carpet from a machine can become extremely tedious. Therefore, there is no guarantee that a person will be able to keep their full attention on the carpet during its entire production time. Also, due to the number of variations possible in the density, pattern and color of carpets, defects in some carpets may be more difficult than in others for the human eye to detect. Further, how well an operator is able to spot defects will depend on many variables including the individual operator's physical abilities (i.e., eyesight), the available lighting, the size of the carpet being observed, and the operator's physical location relative to the carpet. In general, too many variables exist in this form of quality control that a consistent and uniform level of monitoring the production of carpets cannot be assured.
One type of system for monitoring the operation of the machines currently known is the use of a photoelectric detector and a light beam source that detect when yarn used to make the tuff of a carpet falls out of the machine. This system is in no way capable of detecting any of the types of defects that the present invention is directed to monitoring.
All in all, there exists no system or device in industry designed to measure the density of a carpet in order to determine if any defects exist in the manufacture of the carpet. Instead, as shown above, the practices of the industry are limited to very rudimentary techniques that are either too inherently inconsistent or too limited in scope in order to embody a meaningful form of defect detection and monitoring.